Large capacity open pit mining haulage trucks require lifting or jacking to replace worn out or flat tires, for example. Currently, a single lifting ram or cylinder based jack is typically used for this purpose.
However, existing single cylinder jacks have several disadvantages. First, they typically only lift one point or corner of the truck or load at a time. Second, the single cylinder is often heavy and awkward to handle and as such may cause operator injuries and strains. Third, the operator typically needs to stand under the truck while operating the jack and as such the operator may be injured by falling debris from the undercarriage of the truck. Fourth, the operator is typically required to lock the lifted truck via safety stands or lock collars while positioned under the lifted truck, which may be dangerous. Fifth, existing jacks are slow to operate typically requiring approximately 20 to 30 minutes per lift. Sixth, as only one point or corner is lifted at a time by existing jacks, the lifted truck or load may become unstable when the entire front or rear is lifted at one time. Seventh, existing jacks are often unstable when subjected to side loading, for example, when a tire is pulled off the lifted truck. Finally, the cylinders of existing jacks are typically driven by an airline which may freeze up in cold climates.
Under pressure to improve both safety and efficiency while lifting and securing the largest haulage trucks (e.g., up to 400 ton) in the world, mining companies require a safe and cost effective jack for their truck maintenance needs.
A need therefore exists for an improved jack for lifting large capacity trucks and the like. Accordingly, a solution that addresses, at least in part, the above and other shortcomings is desired.